Log replication.metrics shutdown

[fbac]

Log replication metrics shutdown by improving error handling in metrics server and adding signal logging to server shutdown process

• Modifies error handling in the metrics server goroutine in metrics.go to differentiate between normal shutdown errors (http.ErrServerClosed, net.ErrClosed) which are logged at info level and unexpected errors which are logged as errors
• Adds logging of the specific OS signal that triggered server shutdown in the WaitForShutdown method of ReplicationServer in server.go

📍Where to Start

Start with the metrics server goroutine error handling changes in metrics.go.

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Macroscope summarized 8e99dca.

[graphite-app]

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